Rust 2024 Edition Feature Analysis

Feature Availability Check

1. Built-in async fn main() in Standard Library

Status: ❌ Not yet stable

Applicability: ❌ Not applicable

• This project is a library (cdylib), not a binary project
• No main function
• Exposed to Node.js via N-API

2. std::async_iter Async Iterator

Status: ❌ Not yet stable

Applicability: ⚠️ Partially applicable but not stable

• Code has pixel data processing loops (region extraction in screen.rs)
• But this feature is not yet stable and cannot be used
• Current synchronous loops are sufficient

3. async drop Async Destructor

Status: ❌ Still in development

Applicability: ⚠️ Potentially applicable but not stable

• Code has resource management (e.g., Enigo instances)
• But this feature is not yet stable
• Current synchronous Drop trait is sufficient

4. Async Closures (async || {})

Status: ✅ Stable (Rust 1.85.0+)

Applicability: ✅ Can be applied

Applicable Optimizations

Optimization 1: Simplify Code with Async Closures

Although current code is mostly synchronous, async closures can be considered in these scenarios:

1. Delay handling: If async delays are needed in the future, async closures can be used
2. Error handling: Use closures for error handling in async contexts

Optimization 2: Code Style Improvements

Even if some features are not stable, we can still:

1. Use more modern Rust syntax
2. Improve error handling
3. Optimize code structure

Current Code Analysis

Places Already Using Async

• screen.rs: capture_screen_region, get_pixel_color - Already using async fn
• api.rs: Screen::capture, get_pixel_color - Already using async fn

Places Using Synchronous Delays

• mouse.rs: move_mouse_smooth_with_speed - Uses thread::sleep
• keyboard.rs: type_string_delayed - Uses thread::sleep
• mouse.rs: mouse_click - Uses thread::sleep (double-click delay)

Note: These functions are synchronous and exposed via N-API. To make them async, you need to:

1. Change function signature to async fn
2. Ensure N-API supports async functions (confirmed supported)
3. Use tokio::time::sleep instead of thread::sleep

Recommendations

For the following reasons, it is not recommended to immediately convert sync functions to async:

1. API Compatibility: Changing function signatures would break existing API
2. Performance Consideration: For simple delay operations, synchronous thread::sleep is sufficient
3. Feature Status: Most Rust 2024 edition features are not yet stable

Future Optimization Directions

When features become stable, consider:

1. Using std::async_iter: Optimize pixel data processing loops
2. Using async drop: Improve resource cleanup logic
3. Using async closures: Simplify async code structure

Applied Optimizations

1. Replace Loops with Iterator Chains

Location: keyboard.rs - Modifier key handling (3 places)

Before:

for mod_key in mods {
    let key_code = self.parse_key(mod_key)?;
    let _ = enigo.key(key_code, Direction::Press);
}

After:

mods.iter()
    .try_for_each(|mod_key| -> Result<()> {
        let key_code = self.parse_key(mod_key)?;
        let _ = enigo.key(key_code, Direction::Press);
        Ok(())
    })?;

Advantages:

• More functional programming style
• Better error handling (using try_for_each)
• More concise code, conforming to Rust 2024 edition's modern style

2. Optimize Memory Allocation and Batch Operations

Location: screen.rs - Region extraction

Before:

region_buffer.push(raw_buffer[idx]);     // R
region_buffer.push(raw_buffer[idx + 1]); // G
region_buffer.push(raw_buffer[idx + 2]); // B
region_buffer.push(raw_buffer[idx + 3]); // A

After:

region_buffer.reserve((width * height * 4) as usize);
// ...
region_buffer.extend_from_slice(&raw_buffer[idx..idx + 4]);

Advantages:

• Pre-allocate memory, reduce reallocation count
• Use extend_from_slice for batch copying, better performance
• More concise code, reduced repetition

Conclusion

Current code already makes good use of Rust 2024 edition's stable features (like async functions). For features that are not yet stable (async fn main, std::async_iter, async drop), it is recommended to wait for official stabilization before migrating.

Applied optimizations mainly focus on:

1. ✅ Using modern Rust iterator patterns (try_for_each)
2. ✅ Optimizing memory allocation strategy (reserve + extend_from_slice)
3. ✅ Improving code readability and performance

These optimizations make the code more aligned with Rust 2024 edition's modern programming style while maintaining backward compatibility.